"Continuous" therapy is not truly continuous. Down-time adversely affects azotaemic control. Physicians prescribing CRRT should be aware of the consequences of such down-time on the quality and quantity of renal replacement therapy delivered.

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Background/Aims: To determine the impact of replacement fluid infusion site on filter life and azotemic control during continuous veno-venous hemofiltration (CVVH). Methods:Pre-dilution CVVH was conducted from February 2001 to December 2001 and then practice was changed to post-dilution (from January 2002 to July 2002). Filter life was prospectively observed and the following data obtained for each filter: starting date and time, ending date and time, heparin use, heparin dose and protamine use. Daily creatinine, urea, INR, APTT and platelet count were also collected. Results: Forty-eight patients were studied (33 in pre-dilution and 15 in post-dilution) for a total of 309 filters (202 in pre-dilution and 107 in post-dilution). The median filter life was significantly shorter in the post-dilution period (18.0 vs. 13.0 h, p = 0.021). Multivariate linear regression analysis showed that pre-dilution was a significant independent predictor of increased filter life (p = 0.029), together with platelet count (p = 0.0035) and heparin dose (p = 0.046). There was no significant improvement in daily creatinine and/or urea reduction in the post-dilution period (% Δ creatinine: 7.9 vs. 10.2%/day, p = 0.99, urea: 5.4 vs. 9.7%/ day, p = 0.78). Conclusions: Post-dilution was associated with reduced filter life without any beneficial effect on daily changes in urea and creatinine levels. Pre-dilution appears a preferable technical approach to CVVH.

IntroductionDespite studies demonstrating benefit, patients with femoral vascular catheters placed for continuous renal replacement therapy are frequently restricted from mobilization. No researchers have reported filter pressures during mobilization, and it is unknown whether mobilization is safe or affects filter lifespan. Our objective in this study was to test the safety and feasibility of mobilization in this population.MethodsA total of 33 patients undergoing continuous renal replacement therapy via femoral, subclavian or internal jugular vascular access catheters at two general medical-surgical intensive care units in Australia were enrolled. Patients underwent one of three levels of mobilization intervention as appropriate: (1) passive bed exercises, (2) sitting on the bed edge or (3) standing and/or marching. Catheter dislodgement, haematoma and bleeding during and following interventions were evaluated. Filter pressure parameters and lifespan (hours), nursing workload and concern were also measured.ResultsNo episodes of filter occlusion or failure occurred during any of the interventions. No adverse events were detected. The intervention filters lasted longer than the nonintervention filters (regression coefficient = 13.8 (robust 95% confidence interval (CI) = 5.0 to 22.6), P = 0.003). In sensitivity analyses, we found that filter life was longer in patients who had more position changes (regression coefficient = 2.0 (robust 95% CI = 0.6 to 3.5), P = 0.007). The nursing workloads between the intervention shift and the following shift were similar.ConclusionsMobilization during renal replacement therapy via a vascular catheter in patients who are critically ill is safe and may increase filter life. These findings have significant implications for the current mobility restrictions imposed on patients with femoral vascular catheters for renal replacement therapy.Trial registrationAustralian and New Zealand Clinical Trials Registry ACTRN12611000733976 (registered 13 July 2011)Electronic supplementary materialThe online version of this article (doi:10.1186/cc14001) contains supplementary material, which is available to authorized users.